This invention relates to a method and apparatus for recording and/or reproducing signal on or from a recording medium. The present invention also relates to a recording medium for recording signals thereon.
Among the conventional servo formatting systems for recording tracking servo signals on a track of a recording medium for detecting tracking errors, there are a self-formatting system in which servo formatting is performed on the recording medium during signal recording, and a pre-formatting system in which the recording medium is previously formatted prior to its shipment. In a tape-shaped recording medium employed in e.g., a video tape recorder, the self-formatting system is generally employed in view of cost.
A tracking servo signal, recorded on a tape-shaped recording medium in accordance with the conventional self-formatting system, is now explained by referring to FIG. 12.
During data recording, a specified frequency signal is recorded by a leading servo head 51 in a domain T.sub.30 of the tape-shaped recording medium, as shown in FIG. 12A. The signal in a domain T.sub.31 is DC-erased by a recording/reproducing head 52, while the signal in a domain T.sub.32 is DC-erased by a recording/reproducing head 53, for forming a tracking servo signal pattern F.sub.1.
During data reproduction, the servo head 51 pre-traces the same track position as that during data recording for reproducing the tracking servo signal pattern F.sub.1. The reproduced signal is level-detected for deriving a signal V.sub.1 shown in FIG. 12B. The signal V.sub.1 is compared to a reference level m to derive a signal V.sub.2. Subsequently, a sampling pulse SP.sub.1 delayed by time TS.sub.1 from the signal V.sub.2 and a sampling pulse SP.sub.2 delayed by time TS.sub.2 from the signal V.sub.2 are generated. Then, as tracking servo data, data D.sub.1 and D.sub.2 are obtained on sample-holding the level of the signal V.sub.1 by the sampling pulse SP.sub.1 and sample-holding the level of the signal V.sub.2 by the sampling pulse SP.sub.2, respectively. The track position can be detected by comparing the data D.sub.1 and D.sub.2 to each other.
The method for detecting the tracking servo signals from the signals recorded on the recording medium is termed the level difference detecting method.
If, with the above-described tracking servo signal detecting method, fluctuations are incurred in the level of the detected signal V.sub.1, both data D.sub.1 and D.sub.2 are changed, so that the correct track position cannot be detected.
On the other hand, if, when a tape-shaped recording medium, on which a tracking servo signal pattern F.sub.1 has been recorded by a servo head of a signal recording apparatus, is to be reproduced by another signal recording apparatus, the servo head of the second-stated signal recording apparatus has a track width broader than a track width W.sub.1 of the servo head of the first stated signal recording apparatus, there is produced a dead zone in the detected tracking servo signal due to the difference in the track widths of the two servo heads. That is, there are occasions where the tracking servo signals are lowered in detection accuracy under the effects of head tolerances of servo heads provided in the two signal recording apparatus.
In addition, should there be any fluctuations in the widths of the recording/reproducing heads 52, 53, ill effects tend to be produced during recording of the tracking servo signal pattern F.sub.1.